1. Field of the Invention
The present invention is a process for obtaining trimethylhydroquinone by aromatizing 3,5,5-trimethyl-2-cyclohexene-1,4-dione.
2. Description of the Prior Art
Trimethylhydroquinone is a commercially important chemical compound. For example, it is used as an antioxidant for oil and fatty compounds, as an ultraviolet absorber for plastics and rubber, and as an intermediate for the preparation of medicines such as vitamin E (.alpha.-tocopherol).
It has been known to synthesize trimethylhydroquinone by reacting 3,5,5-trimethyl-2-cyclohexene-1,4-dione with an acylating agent, usually an anhydride of carboxylic acid, in the presence of an acid catalyst, then subjecting the resulting diester to basic or acid hydrolysis in order to liberate the trimethylhydroquinone. Such a process is described in German application publication No. 2 149 159. From a production standpoint, the prior art process has several drawbacks. The prior art process on an industrial scale involves the handling, use and replenishment of several reagents in a multi-stage operation, requiring the control of different operating conditions which make continuous processing more complicated and increase the overall production costs. Therefore, there exists a need in the chemical process industry to find a simple and economic process for the preparation of trimethylhydroquinone.